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Chapter 1: What is the main topic discussed in this episode?
Future Proof Extra with Jonathan McRae. Proudly supported by Research Ireland on Newstalk. Now, we live in a world where we are outnumbered by microbes. They are everywhere in, on and around us. And they can do amazing things from improving our mood to surviving in the vacuum of space. But what if they could help us with our plastic pollution problem? My next guest is Ludmilla Aristilda.
She's an environmental engineering professor at Northwestern.
Chapter 2: What role do microbes play in our environment?
She joins me now. Welcome to the program, Ludmilla. This idea of engineering microbes to do good, it's not a new one, but it's a really exciting one. Tell me a little bit about the basics. When we talk about microbes, we're talking about more bacteria than viruses or any type of microbe?
We're talking more bacteria because bacteria have very complex metabolism. They also have the ability to do so many things. As we know, we have beneficial bacteria in our gut that really helps us to be healthy. We also have bacteria in the environment, in soils, for example. We have bacteria that really allows nitrogen and carbon to be recycled in soils. We can also harness bacteria
the ability of bacteria to treat contaminants in the environment.
Chapter 3: How can microbes help reduce plastic pollution?
The idea that bacteria could help us do something like reduce plastic pollution seemed crazy a few decades ago, but this idea has gained traction and we now have bacteria that can break down plastics in our environment. Can you explain how bacteria does something like that?
Yes, so bacteria in general, they have capabilities to digest, hard to digest materials. Like if you think about it, I like to give an example. If you're someone who loves to hike and you walk around a forest or a mountain and you will see wood on the soil, and eventually this wood will be decaying and degrading over a long period of time. And there are microbes that are doing that.
Now the chemistry of this wood, there's a lot of similarity between that chemistry and the chemistry that you'll find in plastics. So we, in my lab, we work on microbes that can do this kind of hard to digest kind of metabolism. And then we went out and explore whether or not they can actually eat plastics as their food.
What is it that's so persistent about plastics again? Because these are from natural resources, right? This is a byproduct of oil, petrochemicals. Yes. These are carbon-based structures. Why are they so persistent and how do the bacteria overcome that?
Yes. So there are different types of plastics. I like to highlight that. So they're so persistent because of their carbon to carbon bond.
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Chapter 4: What types of bacteria are involved in breaking down plastics?
Essentially, it is a bond that is really hard to break. But also there are types of plastics that are easier to break than others because these plastics also have some oxygen that are spiced out within the structure of carbon to carbon bond. Now, what makes it really hard is actually breaking it because plastic is a polymer. So polymer is a repeat of the same unit over and over again.
And it's hard to break because the mycos, what they eat, it's something like sugar or something that is more simpler than a polymer. So in order for a microbe to be able to eat a polymer like a plastic, they first have to break it down into really small pieces and break that down into smaller pieces and then be able to get something that is able to, they can digest.
So there are naturally occurring bacteria that can already do that, is that correct?
Yes.
How did we discover those?
Yes, so in my work specifically, I can give an example. It was observed in the environment. If you find like plastics pellets or microplastics, so microplastics are part of the smaller fragments that I'm talking about. So they're smaller than the original material. And what was reported in the environment, people have observed a certain community of bacteria
they were seeing to be consistently enriched on these microplastics. So then in my lab, we're like, okay, if they're enriching on these small pieces of plastic, then they were found in multiple rivers in city, like urban rivers.
So we asked the question, is it possible that they enrich, you know, these communities of microbes that enrich on these plastics because they can potentially use it as food? And that's how... we went into this kind of path to try to figure this out. And the bacteria that we were specifically working on were isolated from wastewater. So wastewater has a lot of plastics in it.
Yeah.
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Chapter 5: How do bacteria digest hard-to-break materials like plastics?
I mean, if I were to throw a sceptical eye over this, I would say this is interesting work, but it is not a solution to my problem. Is there anything that you see... in your research that suggests that on a major scale we can take the plastic waste that we produce and make any even one hundredth of a percent dent on what we're producing by using bacterial breakdown in this way
Yes, I like to think of it as one of the ways if we're gonna tackle the issue, I think any major issue or global issue shouldn't be tackled with one solution. I believe we should come at it at multiple funds. I think the advantage of microbes is that microbes do not need the waste stream to be pure or to be just one entity. There are some chemical treatments that we can do.
There are other things that we can do that require that you have the waste stream to be just not as complex. The microbes and the bacteria that we're using, they are from the environment. They are used to being exposed to a complex food source.
The other thing I think that is really particular about microbes in general, and I would say specifically the bacteria that we work on, is that we can use the bacteria not just to eat the plastics, but to convert it into a product. This is what's called biomanufacturing. And that's very attractive.
Yeah. And so what sort of products, if a bacteria eats my yogurt pot, what useful output can a bacteria give me?
Again, it depends on the bacterial species. We work with bacteria that produce some acids, so very short, not a lot of carbon chain acids that can be used as a precursor to pharmaceuticals, for example. We have some of the bacteria that we work on that can produce polymers that have structures that are very similar to the polymers that we actually make from petroleum.
That's the part that I'm very excited about. Is there a world in which we can use microbes to turn plastics into precursors to plastics? And that is the circular solution that is very attractive that we as scientists who work in this field would like to achieve.
Yeah. Again, the idea seems great, but the industry required to do this at scale, I mean, I know you say that it's part of the solution, but is this approach realistically not a tiny part of the solution?
I would, I say at this point, we don't know how much is going to be part of like what fraction is going to represent in the total solution. That is way beyond my expertise. But I just wanted, what I could say is that I don't expect this to be the only solution, but also it depends on how much do we invest in this.
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